Brisbane veteran Shannon Campbell has conceded the Lions may have taken St Kilda lightly in Saturday's shock loss, saying they let themselves down as a group.

The Saints were magnificent in securing their fifth win of the season, a 21-point triumph, in the process putting Brisbane into a must-win battle with Melbourne on Saturday night to secure a top-four spot.

Speaking on Tuesday morning, Campbell said it was an "opportunity missed" at the weekend.

"We may have gone into that, maybe, just not expecting St Kilda to bring as much as they did," she said.

"As a group, after the game, we spoke about how we let ourselves down.

"There's no pointing fingers … we just need to fix some things that weren't happening in the game.

"Something on the weekend didn't go our way, we gave away a few free kicks and then we weren't able to get back into the game from there."

Campbell said the Lions had addressed how they needed to change momentum during games that were going against them, including by upping their pressure and staying disciplined.

It was only two matches ago the Lions defeated previously unbeaten Adelaide, and with a victory against North Melbourne earlier in the season, Campbell says they're confident of playing their best against the competition's elite teams.

"We've had two good wins against North Melbourne and Adelaide," she said.

"It seems to be a driving factor. It shouldn't necessarily just be against those top teams, it should be the whole way through, but it always seems to be when we're playing teams like Adelaide and Melbourne that it brings out our best.

"We just need to find that again this week. I don't think we've seen our best footy this year, so hopefully this weekend we can turn it on."

Brisbane is sweating on the fitness of Cathy Svarc and Sophie Conway ahead of facing the Demons after both missed the loss to the Saints.